1. Field of the Invention
The present invention generally relates to display controllers and display apparatuses. More particularly, the invention is directed to a display controller that controls the luminance of an image to be displayed, by changing the number of pulses forming each of display signals applied during a preset display period, and to a display device including the display controller, such as a plasma display panel (PDP).
2. Description of Related Art
Plasma display panels (PDPs) are attracting much attention as a self light-emission, high-luminance display apparatus.
Many conventional PDPs are driven to display video images under luminance control for changing the number of pulses forming each of display signals applied during one preset display period, such as one field period.
In such a PDP driven under the above control, when the average brightness level (often called the “average pulse level (APL)”) of any of externally supplied video signals corresponding to an image to be displayed exceeds a prescribed threshold, a automatic brightness limit (ABL) process is often performed, which limits the luminance of the video signal at which to display the image on the PDP. The ABL process is performed mainly to reduce power consumption in the PDP.
In a specific luminance limiting scheme, some video signals whose APL is equal to or greater than the prescribed threshold have the number of their sustain pulses gradually decreased with increasing APL, and other video signals whose APL is smaller than the prescribed threshold have the number of their sustain pulses kept unchanged. That is, the number of sustain pulses applied to the PDP during a given field period, i.e., the total number of sustain pulses applied during subfield periods into which a single field period is divided, is gradually reduced for any video signal whose APL is equal to or greater than the prescribed threshold, and left unchanged otherwise.
In a conventional display controller for such a PDP, the relationship between the APL and the number of sustain pulses for use in the ABL process is fixed at the time of the PDP's fabrication, for example.
Due to the APL-versus-sustain pulse relationship being fixed for the ABL process in the conventional display controller, no such selective control is available as to allow a user to selectively operate the PDP to increase the lifetime of the PDP by preventing the image burn or decrease the power consumption in the PDP, thus making the PDP functionally inflexible and hence less user-friendly.